"Recessions happen because of a bubble bursting in capital expenditure (as we saw in 2000) or because of a bubble bursting in consumption (as in 2008) or when monetary policy is too tight."

None of that is occurring now, Slok said. "If anything, we are seeing too little capex and consumption." Retail sales were unchanged in July, the worst showing since March.

"Some wobbles" will arise when the Fed finally raises interest rates, but that "won't derail the current expansion," Slok wrote. "That's why I expect equities to continue to rise steadily over the coming years."

Chris Hyzy, chief investment officer of Bank of America's U.S. Trust unit, is optimistic about stocks, too. He thinks the bull market that began in March 2009 and has seen the S&P 500 nearly triple has another 15 years to go.

"I know it sounds easy to say," Hyzy told CNBC. "This is an elongated business cycle. You're going to have fair value through most of it. You're not going to get a lot of overvaluation."